Method of making a toroidal magnetic device



I Dec. 23, 1958 R. R. WHIPPLE METHOD OFMA KING A TOROIDAL MAGNETIC DEVICE Filed March '16. 1953 In van for METHOD OF MAKING A TOROIDAL MAGNETIC DEVICE I Richard R, Whipple, Haverhill, Mass, assignor to Western 1 t c Com a lnscmoratedfle rk. a

corporation of New York Application March 16, 1953, Serial No. 342,398

2 Claims. (Cl. 29-15557) This invention relates to an electromagnetic device and particularly to an electromagnetic device having a toroidal core and a method of making it.

Due to current trends in electronic circuits to mini aturize components, there has been a large demand for toroidal coils and transformers having cores of small sizes with many turns of very fine wire wound thereon.

While winding machines with circular shuttles have been used for many years with fairly good results on various sizes of complete toroidal cores, each turn of wire being threaded through the central hole of the toroidal core, they are unsuitable for winding cores of very small sizes since the central hole of the torus is too small to accommodate the shuttle.

Segmented cores have been used in an effort to satisfy the demand for these miniaturized components, the windings being placed or wound on each of the core segments, the segments then being joined and the windings on the segments connected to give the desired circuit. Due to the necessity of using a clamp on some portion of each segment of the core while winding and since it is not possible to have the winding extend completely to the free end of the segment, windings on these cores cover substantially less than the full 360 of the assembled core. As a result, devices produced by this method depart from the ideal uniform distribution of magnetomotive force around the core ring and therefore the resultant leakage inductance is considerable, especially at the junctions of the segments.

It is, therefore, the principal object of this invention to provide an improved electromagnetic device having a segmented toroidal core with a substantially full 360 winding and a method for making it in a simple and inexpensive manner.

According to the general features of the invention, this object is attained by applying flanged, winding-supporting tubes to the ends of each segment of the core, one end of each segment protruding beyond the flange of its tubular member and the other end thereof recessed a like amount within the other tubular member, applying to the segments windings which extend over the segments and tubes thereon to the flanges, and assembling the segments to form a toroidal device with a substantially continuous core. A device produced by this process has substantially a full 360 winding and the junctions of the flanges are circumferentially displaced from the junctions between the segments.

These and other features of the invention will be better understood from the following detailed description and accompanying drawing in which:

Fig. 1 is a plan view of a segment of a toroidal core having tubular winding supporting members attached to the ends thereof mounted to a clamping member of a winding machine, the clamping and tubular members being partially broken away; and e Fig. 2 is a plan view of a toroidal coil embodying the features of the invention, having partially broken away sections to show the construction thereof.

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Referringjnow to Fig. 1 of the dr, wing reference nume'ral 3 designates one of two essentially equal segments of a toroidalcore which are, in this instance, obtained bycracking a complete pressedpermalloydust toroidal coreat the desired locations with a conventional knifeedge cracking tool. Thin, flanged, cellulose acetate tubular members 4 are secured to the ends 5and'8 ofthe seg. ment, the end. 5 of. the segment protruding beyond the flange "6 of the tubular member a distance sufficient to receive a clamping member '7 ofa coil winding machine which may be of the type disclosed in applicants co-pending application Serial No. 320,191, filed November 13, 1952 now Patent No. 2,773,651 and the other end 8 recessed a like distance within the other tubular member.

A winding 9 (Fig. 2), extending the full distance between the flanges 6 of the tubular members 4, is then applied to the segment and the tubular members.

The other half core segment 10 is similarly processed, however, in this case, since these are cracked core segments, they should be re-assembled in the same relationship as they were parted, therefore, the segment end corresponding to end 5 of segment 3 will be recessed within the flanged tubular member secured thereon and the end corresponding to end 8 of core segment 3 will protrude beyond the flange of the tubular member secured thereon. A suitable commercial type cement is then applied to the ends of the broken core segments and the segments are re-assembled in the same relationship as they were parted and the windings of the segments are connected to give the desired circuit.

Fig. 2 discloses an assembled coil wherein the windings of the two segment halves are connected by a conventional splice 11 to result in a series-aiding circuit to form a single circuit inductor having ends 12 and 13.

While this invention has been described with respect to a particular embodiment for purposes of illustration, it will be understood that the device could be modified in various ways in accordance with the general principles of the invention and the requirements of the particular conditions of use. For example, the core may be divided into more than two segments; the segments may have cut or pre-formed ends; difierent types of core materials may be used depending on the requirements of the device; the winding-supporting tubular members may be made of other non-conducting materials; or multiple windings may be applied to each segment and connections made to each to form a transformer instead of an inductor.

These and numerous other arrangements may be devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. The method of making a toroidal electromagnetic device with a substantially radially segmented toroidal core which comprises applying a non-conductive flanged, winding supporting tube having an inner diameter slightly larger than the outer diameter of the segment to the ends of each segment of the core whereby one end of each segment protrudes beyond the flange of the tubular member secured thereto and the other end is recessed a like distance within the other tubular member thereon, applying a winding on each segment and the tubes thereon which winding extends the full distance between the flanges, assembling the segments by telescoping the unwound portion of one segment within the winding protruding end of another segment to form a coil having a continuous core and a substantially full 360 degree winding, and interconnecting the windings on the segments in a desired circuit arrangement.

2. The method of making a toroidal electromagnetic device with a substantially full 360 degree winding which comprises applying a non-conductive winding support ing tube, with a flange extending from one end thereof,

I larg'er' than'thediameter of the segments to receive the 1 ends of the'segments therein, applying a winding on each segment'between the flange and a point short of, the end, opposite the tube supporting end, a distance substantially equal to said predetermined distance, assembling the Wound segments in telescoping arrangement by inserting the unwound end of each segment into a tube opening of another segment, andfinterconnecting the windings on the segments in a desired circuit arrangement.

UNITED STATES PATENTS Colpitts Nov. 3, 1914 Wood July 21, 1925 Purdy Mar. 4, 1930 Clemons Feb. 14, 1933 Koschmieder May 13, 1941 Ehrman Mar. 8, 1949 Wiegand Feb. 28, 1950 Stein June 26, 1951 Ford Feb. 19, 1952 

